Mounting
Leuze electronic MLC 510 20
Calculation of safety distanceS
RT
for access guarding
S
RT
[mm] = Safety distance
K [mm/s] = Approach speed for access guarding with approach direction orthogonal to the protective field:
2000mm/s or1600mm/s, when S
RT
>500mm
T [s] = Total time of the delay, sum from (t
a
+t
i
+t
m
)
t
a
[s] = Response time of the protective device
t
i
[s] = Response time of the safety relay
t
m
[s] = Stopping time of the machine
C
RT
[mm] = Additional distance for access guarding with approach reaction with resolutions of 14to40mm,
d=resolution of protective device C
RT
=8×(d-14)mm. Additional distance for access guard-
ing for resolutions>40mm: C
RT
=850mm (standard value for arm length)
Calculation example
Access to a robot with a stopping time of 250ms is to be safeguarded with a safety light curtain with 90mm
of resolution and 1500mm of protective field height whose response time is 6ms. The safety light curtain
directly switches the contactors whose response time is contained in the 250ms. An additional interface
therefore does not have to be taken into consideration.
Ä Calculate safety distanceS
RT
using the formula acc. to ISO13855.
K [mm/s] = 1600
T [s] = (0.006+0.250)
C
RT
[mm] = 850
S
RT
[mm] = 1600mm/s×0.256s+850mm
S
RT
[mm] = 1260
This safety distance is not available in the application. This is why a new calculation is done with a safety
light curtain with 40mm of resolution (response time=14ms):
Ä Re-calculate safety distanceS
RT
using the formula acc. to ISO13855.
K [mm/s] = 1600
T [s] = (0.014+0.250)
C
RT
[mm] = 8×~(40-14)
S
RT
[mm] = 1600mm/s×0.264s+208mm
S
RT
[mm] = 631
The safety light curtain with a 40mm resolution is thus suitable for this application.
NOTICE
For the calculation with K=2000mm/s, safety distanceS
RT
equals 736mm. The adoption of ap-
proach speed K=1600mm/s is therefore permitted.